But the room is now top secret, and closely guarded.

For one thing, they were closely guarded by their owners.

As such, it was closely guarded on both sides of the river.

Their security, he said, was a top priority, and they were being closely guarded.

I should have thought things were much too strict and closely guarded.

The different design companies closely guard this as proprietary information.

"This is a culture where personal availability has been closely guarded."

If he had aspirations to higher office, they were closely guarded.

Every sensitive point on the island would be closely guarded.

The company closely guards the process, perfected over the last 36 years.